With the engine running, spray the underside of the belt, as near as possible to the source of the noise, Gates officials say. The water acts as a lubricant, and how the system reacts to its application can reveal the problem.
“If the squealing immediately becomes more pronounced when the belt is sprayed, this indicates insufficient belt tension. This is because the water has been allowed to get between the belt and the pulley, causing hydroplaning and loss of traction - belt slip.
“Proper tension will squeeze the water out of the pulley ribs and prevent hydroplaning. Replace the belt and the tensioner to rectify the problem.”
If the noise is intermittent - “chirping” - this probably indicates a misalignment problem, say officials. Again, spray the water near as possible to the source of the noise. If the noise dissipates momentarily and the noise returns, “this confirms misalignment (or a bent or warped pulley) somewhere in the system.
“The chirping is caused by the belt reacting to lateral forces against the ribs as it ‘rides’ the bent or misaligned component. In this case, the water lubricates the belt momentarily, reducing the noise. Once the moisture boils out, the friction noise returns.”
Locate the misaligned or damaged components and adjust or replace as necessary, they say. Use the Gates’ Belt Wear Gauge to evaluate the remaining service life of the belt and replace if appropriate.
“Whenever any components of the ABDSystem are serviced or replaced, it is vital to inspect and clean all pulleys, idlers and other belt mating surfaces to prevent the premature start of another wear cycle on the belt.”
A SYSTEMS ISSUE
The Accessory Belt Drive System on a modern vehicle is a complex and important subsystem that provides reliability, safety and passenger comfort. “Although the serpentine belt and automatic tensioner are relatively inexpensive components of the system, their proper adjustment and operation are vital to the functioning of the system and the longevity of other - more expensive - components,” Gates officials sum up.
Changes in serpentine belt construction have provided longer life and higher reliability, but these new materials require a different method for diagnosing belt wear itself, as well as how symptoms of other ABDSystem problems are revealed in damage patterns on the belt, officials say. Understanding the effects of this new belt construction on both system life and problem diagnosis is key to maintaining these systems at top efficiency.
Technical Editor Dave Cappert takes a look at timing-belt service, as well as some of the specialty tools required by some OEMs for the service.